Related Experiment Videos
Subclasses of platelet 3H-imipramine binding sites
1Department of Psychiatry and Human Behavior, University of California, Irvine 92717.
Psychiatry Research
|December 1, 1990
Summary
This study investigated high-affinity binding sites for 3H-imipramine (3H-IMI) on blood platelets. Results suggest two distinct binding sites exist, one protein-based and sensitive to cyanoimipramine (CNIMI), the other non-protein and resistant.
Area of Science:
- Pharmacology
- Biochemistry
- Neuroscience
Background:
- High-affinity binding sites for 3H-imipramine (3H-IMI) are implicated in serotonin reuptake inhibition.
- Understanding the nature of these binding sites is crucial for elucidating drug mechanisms and platelet function.
Purpose of the Study:
- To investigate the potential presence of multiple high-affinity 3H-IMI binding sites on human blood platelets.
- To characterize the properties of these binding sites using enzymatic digestion and specific inhibitors.
Main Methods:
- Platelet membranes were treated with trypsin to assess proteinaceous binding sites.
- Cyanoimipramine (CNIMI), a pseudo-irreversible inhibitor, was used to differentiate binding site populations.
- Displacement assays with desipramine were employed to define total high-affinity binding.
Main Results:
- Increasing concentrations of CNIMI revealed a discontinuous binding curve, indicating multiple affinity states.
- Approximately half of the high-affinity 3H-IMI binding sites were sensitive to 0.25 nM CNIMI.
- Trypsin pretreatment yielded similar results to CNIMI treatment, with no additive inhibitory effects when combined.
Conclusions:
- The findings strongly suggest the existence of at least two distinct high-affinity 3H-IMI binding sites on blood platelets.
- One site is likely proteinaceous and sensitive to CNIMI, while the other appears non-proteinaceous and CNIMI-resistant.